The present invention disclosed herein relates to a microfluidic device and microfluidic analysis equipment.
Typical biochips quickly detect analytes such as biomaterials or environmental materials using membranes or hygroscopic papers. For example, biochips may be used for pregnancy diagnostic apparatuses, apparatuses for measuring hormones such as human chorionic gonadotropin (HCG), and alpha fetoprotein (AFP) (this is used as a liver cancer biomarker) measurements, which are currently commercialized. Biochips realized using membranes are disadvantageous for adjusting the flow of microfluid. The membranes may be formed of a polymeric material having a predetermined thickness and pores. Thus, the membranes are used for a simple test that determines whether an analyte is present at a previously set concentration or more. However, uniformity of sizes of the pores formed in the membranes is below the level required for an accurate test. In addition, if the sizes of the pores within the membrane are determined, strength of a capillary force is also determined. As a result, since it is impossible to adjust a microfluidic flow velocity in the membrane, the biochip realized using the membrane is not suitable for testing to accurately quantify the concentration of an analyte.
Alternatively, to overcome such limitations, there is a method which uses a microchannel as a passage for transferring a fluid. Based on hydrodynamics, a technology is widely used, which adjusts microfluidic flow velocity using microchannels with different widths and depths, and configurations of the microchannels are controlled to increase and decrease capillary force. There are many limitations in a typical biochip field in which a constant transfer velocity of the fluid in a microchannel, a constant reaction time in a reaction region, and a transfer stopping ability of fluid are necessary for quantifying analytes. Biochips using only capillary action are limited in that only the configuration and size of a channel are adjusted to accurately control fluid flow. Although a method in which an inner wall of the channel is surface-treated to have a hydrophilic property or a hydrophobic property to control the fluid was attempted, it is difficult to realize a biochip having a function that stops the fluid at a desired position and transfers the fluid to a desired position. For example, there is a technique in which a hydrophilic region of a capillary is defined to prevent the fluid from flowing so as to maintain constant reaction time. When the fluid reaches the hydrophilic region, the fluid flow is stopped due to a property in which the inner wall of the channel pushes the fluid. In general, most materials tend to have the hydrophilic property at the initial stage. However, if the materials contact the fluid for a long time, the materials tend to convert to the hydrophobic property. Thus, the fluid passes through the hydrophilic region at a very slow speed. During this time, the fluid is stopped in the channel in proportion to the surface area of the hydrophilic region. When the reaction time is controlled using such a method, a specific section of the channel should have the hydrophobic property. Thus, a suitable material and a processing method should be contrived in consideration of a physicochemical property of the fluid to be used. Also, in the case where the hydrophilic region of the channel is defined to prevent the fluid from flowing so as to maintain constant reaction time, there is a limitation that the hydrophilic property is insecure in the hydrophilic region due to absorption of atmospheric moisture, the amount of a reaction material, and inertial force of fluid flow in the reaction region. As a result, the reaction material within the reaction region may flow into the hydrophilic region.
There is a method in which pressure and electric energy are used to transfer and treat a fluid within a microfluidic device. In the case where pressure is used, a separate pressure regulator (e.g., a syringe pump or a peristaltic pump) is required, and the volume of a diagnosis system including a microfluidic device increases. In addition, the system price is affected by the pressure regulator more than the microfluidic device. Thus, this technique is unsuited for a point of care system (POCS) market in which a microfluidic device having a small size and a low price is required. On the other hand, it is advantageous that a relatively small system may be used in a method in which a fluid flow is controlled using an electrokinetic technique when compared to the method using pressure. However, a method for controlling the fluid using the electric energy may be used very limitedly. To apply the electric energy, an electrode should be provided in the microfluidic device. Accordingly, a unique configuration and method should be provided according to a property of the fluid, and various devices for transferring an electrical signal into the microfluidic device should be disposed in combination. Thus, it is complicated to manufacture and realize the system even if the system is small. Specifically, when many reaction processes are performed in one microfluidic device, the electric energy should be adjusted for each process in the case where the electrical property of the fluid is changed in each process. Therefore, the above-described method may be very complicated and difficult.